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wax moth destruction

You can always buy more bees, catch a swarm, make a split, or otherwise replace bees. But drawn comb can not be purchased. Having drawn comb in early spring exponentially increases a colony’s productivity versus starting on foundation. A spring package placed on drawn comb typically makes surplus honey the same year.

After the nectar flow, beekeepers must protect their drawn comb from wax moths which will take every opportunity to destroy your bee’s legacy.  You may have to store drawn comb after pulling honey supers, extracting, removing dead outs or removing excess hive bodies as the bee colony population reduces. Always remember, drawn comb is beekeepers’ gold and should be saved and preserved until placed back into use the following spring.

Here are a few excerpts from emails discussing protecting drawn comb from wax moths during storage:

Wax moths are attracted to older brood comb. The residual proteins found in brood comb are their attractant. Typically they will not show any interest (or minimal) in the clean white wax found in honey supers. If any of the comb on a frame has been used at any time in the past for brood rearing it is subject to wax moth infestation.

Be thankful they are on plastic foundation. Otherwise you often have to replace the foundation. And if they are in wooden frames wax moths will actually bore holes in the wood as well. On plastic you can scrape it off and re-coat with wax for next year.

On placing frames in the freezer to kill the wax moth eggs: You can google wax moth, life cycle, etc and find some research. The success of killing the larvae and eggs is dependent on temperature and length of time of exposure. Two days may be sufficient IF your freezer is at 0 degrees F. If your freezer is kept at 20 degrees F it may take 6 days. And if at 32 degrees F it may take longer. (These are just guesses but perhaps you get the idea that an overnight in the freezer may not do the job.) Some people with a limited number of frames can store them in the freezer until outdoor temperatures are colder.

In the bee yard, there is a temperature range for wax moth reproduction. When the outdoor temperatures get cool enough (typically after first freeze) they are typically no longer a threat.

Every year we get posts on the Mid-State Beekeepers discussion board with pictures saying they froze the comb for X number of days then placed it in a Tupperware or other container and stored under the house or some similar dark place only to find the comb destroyed by spring. Last year in bee school a member of the class asked me about this specifically and said if he placed the frames in the freezer for X number of days and then immediately placed it in lawn trash bags and sealed them completely shouldn’t that work? I told him that “in theory” his plan would work but my experience is some eggs will hatch, a mouse will chew a hole, etc., and if conditions are right they will destroy his comb.

On Paramoth (paradichlorobenzene) crystals: The approved product for use with stored comb, and properly labeled, is Paramoth. Moth balls and crystals found in dollar stores, Walmart, and elsewhere may not be pure paradichlorobenzene or worse yet, may be another chemical, naphthalate a known carcinogenic.

Paramoth works well but it is not a one and done application. Use them according to the label and do not under-dose. The crystals “melt” as they release their gas into the supers. Periodically check them throughout the storage period (or until the weather turns cold) and replenish them as needed. I’ve seen some people tape the edges of the hive bodies to make a gas seal. Unfortunately this dark, sealed environment is also ideal for the moths when the para-moth dissolves and no longer provides protection. A period of airing out is necessary before placing the comb back into use.

Storing drawn comb using open air, light, and breeze: I did this one year with good success by placing the hive bodies on their sides under a covered overhang. The light, air, and breeze is an uninviting environment for the moths. This takes a bit of work to lay out the area such that all of the needed components are present AND the frames are protected from the elements. But if you only have a few hive bodies it’s possible. Also, be aware that anything placed outside is subject to squirrels, mice, and other hungry travelers who like the comb, pollen, and honey residuals.

Bacillus thuringiensis aizawa returns! BT (bacillus thuringiensis aizawa): BT is a gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide. This works well and in past years was recommended by the Xerces Society as an approved organic control. Some years ago BT was on the market for use by beekeepers as a product to control wax moths in stored frames until its registration expired and was not renewed by the manufacturer. It has again been registered for use and should start showing up at your favorite beekeeping supply house soon. I have not yet seen it on websites nor in the catalogs. (Word in the bee yard says call Dadant by phone and they’ll hook you up.)  A June 2020 article titled: Valent BioSciences Partners with Vita Bee Health to Develop New Biological Wax Moth Control That Safeguards Health of Honeybees indicates it’s returning to the market. I have a friend that uses BT and sprays the comb as it is coming out of the extractor. Care must be taken to protect the BT sprayed comb from temperatures above 86F degrees  as the bacterium can not survive at higher temperatures. More information can be found in this January release by ABJ here.

Final notes on BT: 1) Bacillus thuringiensis kurstaki readily available in garden centers is not the same as bacillus thuringiensis aizawa. 2) There is a product called XenTari for use as non chemical, organic bio control method and approved for use on organic crops is also Bacillus thuringiensis, aizawai. However it is not approved for use as a control for wax moths on comb nor labeled as such. Remember, use of non approved chemicals without proper labelling places the beekeeper at risk should someone claim harm after eating honey from hives where pesticides were not used in accordance with the law.

In closing, for those who protect their drawn comb now, next spring will pay huge dividends in the way of easy splits and surplus honey. And for those who choose to not protect their drawn comb from wax moths don’t despair, I understand the larvae are great as fishing bait.

You can read more about the Greater Wax Moth here: https://en.wikipedia.org/wiki/Galleria_mellonella

And on the Lesser Wax Moth here: https://en.wikipedia.org/wiki/Lesser_wax_moth